The present invention relates to an electrical switch and, more particularly but not exclusively, to a rotary switch.
An electrical switch of the type concerned typically comprises a casing, an internal rotor, a moving contact mounted on the rotor for rotation, and a plurality of fixed contacts in the casing for short-circuiting by the moving contact. Whilst the moving contact can be designed to provide different switching combinations between the fixed contacts, the variation of such combinations has been found to be rather limited, primarily by reason of the invariable design of the fixed contacts.
The invention seeks to mitigate or at least alleviate such a problem by providing an improved electrical switch.
According to the invention, there is provided an electrical switch comprising a casing and a rotor supported within the casing for rotation about an axis. The rotor has a first surface extending around the axis and a second surface extending transversely of the axis. A moving contact is mounted on the rotor for rotation therewith, which has first and second inter-connected parts adjacent the first and second rotor surfaces respectively. A plurality of fixed contacts is located laterally of the rotor for short-circuiting by the moving contact wherein the switch is closed. At least one of the fixed contacts has first and second inter-connected parts bearing resiliently against the first and second rotor surfaces respectively for contact with the corresponding first and second moving contact parts according to the angular position of the rotor.
Preferably, the first and second surfaces of the rotor includes recesses locating the first and second parts of the moving contact respectively, therein accommodating their thickness.
It is preferred that the rotor has a generally flat cylindrical body including a peripheral surface as its first surface and one of its end surfaces as the second surface.
In a preferred embodiment, the second moving contact part extends partially round the axis, and the first moving contact part extends substantially at right angles relative to the second part.
More preferably, the moving contact has a generally flat body that is folded to form its first and second parts.
It is preferred that the second part of said one fixed contact extends substantially at right angles relative to the first part.
It is further preferred that said one fixed contact has a body that comprises a base bent to form the first part and a side portion folded about the base to form the second part.
It is yet further preferred that the base of the fixed contact body is generally Z-shaped, having one end acting as the first part, the opposite end acting as a terminal for connection with an electric cable, and a middle section from which the side portion extends.
It is yet further preferred that the fixed contact body is generally T-shaped prior to the formation of its parts through bending and folding.
In a specific construction, the casing has a substantially square shape, including a pair of diametrically opposite corners, within each of which a respective said one fixed contact is located.
More specifically, in an embodiment the second moving contact part extends over 180xc2x0 round the axis.
As an example, the electrical switch is a rotary switch with the rotor being rotatable over 360xc2x0 in opposite directions.